SAP SELECT EXCEPT MIN GTT ABEXA

Get Example source ABAP code based on a different SAP table
  SAP Help

SELECT, Difference with Global Temporary Table
This example demonstrates a difference across a table and a global temporary table (GTT).

ABAP_SOURCE_CODE
DEMO CL_DEMO_SELECT_EXCEPT_MIN_GTT

ABAP_DESCRIPTION
This example has the same result as the executable example for a difference with aggregate expression . Here, however, the SELECT statement is split into two AB-SQL statements for demonstration purposes:

The aggregation is performed in the subquery of an INSERT statement whose result set is written to a global temporary table (GTT).

EXCEPT is used to create the difference of the result set of a SELECT statement on the table SFLIGHT and a SELECT statement on the GTT.
The GTT must be cleared explicitly before the end of the execution to prevent the runtime error COMMIT_GTT_ERROR in the next implicit database commit.